Method for automatically verifying the presence of members for holding preforms in a heating station

Abstract

Provided is a method for verifying holding members in a heating station equipped with a device for transporting the preforms. The device includes a plurality of movable supports circulating in a closed circuit and members for individually holding the preforms by their neck, where each of the holding members is borne by a movable support. The method includes setting the movable supports in movement to bring them successively into an acquisition zone, acquiring an image of each individual holding member in the acquisition zone, and automatically verifying the presence of a holding member on each of the images taken.

The invention claimed is: 
     
       1. A method for automatically verifying the presence of holding members ( 30 ) for holding preforms ( 12 ) made from a thermoplastic material in a heating station ( 10 ), the heating station ( 10 ) being provided with a transport device ( 28 ) for transporting the preforms ( 12 ) along a heating tunnel ( 22 ), the transport device ( 28 ) comprising:
 a plurality of movable supports ( 32 ); 
 individual holding members ( 30 ) for holding the preforms ( 12 ) by their neck ( 16 ), each of the holding members ( 30 ) being borne by a movable support ( 32 ), the holding members ( 30 ) being removably fixed to their respective movable supports ( 32 ); 
 wherein the method comprises: 
 a step (E 1 ) of setting the movable supports ( 32 ) in motion in order to bring them in succession into an acquisition zone (Z 1 ); 
 a step (E 2 ) of acquiring an image of each individual holding member ( 30 ) as each of the movable supports ( 32 ) passes through the acquisition zone (Z 1 ), by means of an image capturing device ( 78 ); 
 a step (E 3 ) of automatically verifying the presence of a holding member ( 30 ) on each of the images taken during the acquisition step (E 2 ), by computer processing of each of the images by means of an electronic control unit ( 60 ). 
 
     
     
       2. The method as claimed in  claim 1 , wherein when at least one holding member ( 30 ) is detected as being absent from a movable support ( 32 ) during the verification step (E 3 ), the electronic control unit ( 60 ) emits a warning signal. 
     
     
       3. The method as claimed in  claim 1 , wherein the holding member ( 30 ) is formed by a mandrel suitable for being inserted into a neck ( 16 ) of one of the preforms ( 12 ), each holding member ( 30 ) being suitable for being replaced during a change in format of the preforms ( 12 ) in order to adapt an outer diameter (D 3 ) of the holding member ( 30 ) to an inner diameter (D 2 ) of the neck ( 16 ) of the preform ( 12 ). 
     
     
       4. The method as claimed in  claim 3 , wherein the method is triggered after the start of a replacement of the holding members ( 30 ), before the heating station is started up. 
     
     
       5. The method as claimed in  claim 4 , wherein the heating station ( 10 ) comprises:
 at least one pair of longitudinal ramps ( 54 ) that define a slot ( 56 ) for the preforms ( 12 ) to travel through, at least one of the ramps ( 54 ) being transversely movable in order to vary the width of the slot ( 56 ); 
 at least one motorized device ( 58 A) for transversely moving the at least one movable ramp ( 54 ) in order to adapt the width of the slot ( 56 ), said motorized device ( 58 A) being automatically controlled by the electronic control unit ( 60 ). 
 
     
     
       6. The method as claimed in  claim 5 , further comprising:
 a step (E 5 ) of automatically determining the outer diameter (D 3 ) of the holding member ( 30 ) by computer processing of at least one of the images taken during the acquisition step (E 2 ); 
 a step (E 6 ) of automatically adjusting the width of the slot ( 56 ) by moving the at least one movable ramp ( 54 ) as a function of the outer diameter (D 3 ) determined during the determining step (E 5 ) in order to adapt the width of the slot ( 56 ). 
 
     
     
       7. The method as claimed in  claim 1 , wherein, during the acquisition step (E 2 ), the image capturing device ( 78 ) takes an image of the profile of the holding member. 
     
     
       8. The method as claimed in  claim 7 , wherein the image capturing device ( 78 ) is arranged at a predetermined distance (C) from the holding member during the image acquisition operation. 
     
     
       9. The method as claimed in  claim 6 , wherein a model of the holding member is determined by recognition of a visual mark borne by each of the holding members. 
     
     
       10. The method as claimed in  claim 8 , wherein during a determining step (E 5 ), the outer diameter (D 3 ) of the holding member ( 30 ) is obtained by multiplying a width of the holding member ( 30 ) measured on the image by a predetermined proportionality coefficient (K). 
     
     
       11. The method as claimed in  claim 8 , wherein during a determining step (E 5 ), an outline of the holding member ( 30 ) shown on the image is compared with outlines of holding members ( 30 ) stored by the electronic control unit ( 60 ), each stored outline being associated with an outer diameter (D 3 ) stored by the electronic control unit ( 60 ).